Abstract: Disclosed is a junction device for assembling a PLC (Planar Lightwave Circuit) chip and an optical-fiber block used in an optical-communication system. The junction device includes: an ultraviolet-hardening adhesive filled into a space between the interfaces of the PLC chip and the optical-fiber block, the interfaces being inclined at a given angle; an ultraviolet-light source positioned over the ultraviolet-hardening adhesive for hardening the ultraviolet-hardening adhesive; an optical sensor positioned under the ultraviolet-hardening adhesive for measuring the power changes in the ultraviolet output that have penetrated through the ultraviolet-hardening adhesive; an optical power-meter for displaying the power changes of the ultraviolet based on the data received from the optical sensor; and, a controller for detecting when the ultraviolet-hardening adhesive is completely hardened based on data received from the optical power-meter.